Compact lidar systems for vehicle contour fitting

ABSTRACT

An apparatus of a light detection and ranging (LiDAR) scanning system for at least partial integration with a vehicle is disclosed. The apparatus comprises an optical core assembly including an oscillating reflective element, an optical polygon element, and transmitting and collection optics. The apparatus includes a first exterior surface at least partially bounded by at least a first portion of a vehicle roof or at least a portion of a vehicle windshield. A surface profile of the first exterior surface aligns with a surface profile associated with at least one of the first portion of the vehicle roof or the portion of the vehicle windshield. A combination of the first exterior surface and the one or more additional exterior surfaces form a housing enclosing the optical core assembly including the oscillating reflective element, the optical polygon element, and the transmitting and collection optics.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application Ser. No. 63/220,455, filed Jul. 9, 2021, entitled “COMPACT LIDAR SYSTEMS FOR CONTOUR FITTING,” the content of which is hereby incorporated by reference in its entirety for all purposes.

FIELD OF THE TECHNOLOGY

This disclosure relates generally to optical scanning and, more particularly, to an apparatus of a light detection and ranging (LiDAR) scanning system for at least partial integration with a vehicle.

BACKGROUND

Light detection and ranging (LiDAR) systems use light pulses to create an image or point cloud of the external environment. Some typical LiDAR systems include a light source, a light transmitter, a light steering system, and a light detector. The light source generates a light beam that is directed by the light steering system in particular directions when being transmitted from the LiDAR system. When a transmitted light beam is scattered by an object, a portion of the scattered light returns to the LiDAR system as a return light pulse. The light detector detects the return light pulse. Using the difference between the time that the return light pulse is detected and the time that a corresponding light pulse in the light beam is transmitted, the LiDAR system can determine the distance to the object using the speed of light. The light steering system can direct light beams along different paths to allow the LiDAR system to scan the surrounding environment and produce images or point clouds. LiDAR systems can also use techniques other than time-of-flight and scanning to measure the surrounding environment.

SUMMARY

Most LiDAR systems to date are rather bulky and protruding when mounted on top of a vehicle, making them unattractive in terms of aerodynamics and vehicle styling, and impractical for manufacturing for mass deployment. Compact LiDAR systems do exist, but often with the compact design, it is accompanied by sacrifice to the receiving aperture and therefore may negatively impact long distance detection performance. Embodiments of the invention disclosed herein propose novel designs optimized with overall vehicle aerodynamics in mind, so that the LiDAR system is compact and may be integrated seamlessly into the top portion of the vehicle.

In one embodiment of the disclosed invention, the LiDAR system's optical core assembly is set up with a reduced height, while still maintaining the receiving aperture needed to detect far objects. The transceiver optics are further optimized to enable a tapered vertical profile from front to back, so that the whole LiDAR system unit can be placed above the vehicle's windshield with minimal protrusion, with a top surface that is substantially flush with the vehicle's roof.

An apparatus of a light detection and ranging (LiDAR) scanning system for at least partial integration with a vehicle is disclosed. The apparatus comprises an optical core assembly including an oscillating reflective element, an optical polygon element, and transmitting and collection optics. The apparatus includes a first exterior surface at least partially bounded by at least a first portion of a vehicle roof or at least a portion of a vehicle windshield. A surface profile of the first exterior surface aligns with a surface profile associated with at least one of the first portion of the vehicle roof or the portion of the vehicle windshield. A combination of the first exterior surface and the one or more additional exterior surfaces form a housing enclosing the optical core assembly including the oscillating reflective element, the optical polygon element, and the transmitting and collection optics.

BRIEF DESCRIPTION OF THE DRAWINGS

The present application can be best understood by reference to the figures described below taken in conjunction with the accompanying drawing figures, in which like parts may be referred to by like numerals.

FIG. 1 illustrates one or more exemplary LiDAR systems disposed or included in a motor vehicle.

FIG. 2 is a block diagram illustrating interactions between an exemplary LiDAR system and multiple other systems including a vehicle perception and planning system.

FIG. 3 is a block diagram illustrating an exemplary LiDAR system.

FIG. 4 is a block diagram illustrating an exemplary fiber-based laser source.

FIGS. 5A-5C illustrate an exemplary LiDAR system using pulse signals to measure distances to objects disposed in a field-of-view (FOV).

FIG. 6 is a block diagram illustrating an exemplary apparatus used to implement systems, apparatus, and methods in various embodiments.

FIG. 7 illustrates perspective and side views of several mounting options for an exemplary LiDAR system on an autonomous driver motor vehicle.

FIG. 8 illustrates a front view of an exemplary LiDAR system integrated into a roof and windshield portion of a motor vehicle.

FIG. 9 illustrates a side view and a zoom-in side view of an exemplary LiDAR system design in a motor vehicle.

FIG. 10 illustrates a flow diagram for a LiDAR signal chain according to embodiments of the disclosed invention.

FIG. 11 illustrates the path of a LiDAR signal using an exemplary apparatus for a LiDAR optical engine according to embodiments of the disclosed invention

FIG. 12 illustrates a cross-sectional view of a tapered design of a LiDAR system in accordance with one embodiment of the disclosed invention.

FIG. 13 illustrates two exemplary embodiments of a positioning a transmission beam.

FIG. 14 illustrates a top view of an exemplary LiDAR tapered system design.

FIG. 15 illustrates a top view of an exemplary LiDAR system design in accordance with one embodiment of the disclosed invention.

DETAILED DESCRIPTION

To provide a more thorough understanding of the present invention, the following description sets forth numerous specific details, such as specific configurations, parameters, examples, and the like. It should be recognized, however, that such description is not intended as a limitation on the scope of the present invention but is intended to provide a better description of the exemplary embodiments.

Throughout the specification and claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise:

The phrase “in one embodiment” as used herein does not necessarily refer to the same embodiment, though it may. Thus, as described below, various embodiments of the disclosure may be readily combined, without departing from the scope or spirit of the invention.

As used herein, the term “or” is an inclusive “or” operator and is equivalent to the term “and/or,” unless the context clearly dictates otherwise.

The term “based on” is not exclusive and allows for being based on additional factors not described unless the context clearly dictates otherwise.

As used herein, and unless the context dictates otherwise, the term “coupled to” is intended to include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements). Therefore, the terms “coupled to” and “coupled with” are used synonymously. Within the context of a networked environment where two or more components or devices are able to exchange data, the terms “coupled to” and “coupled with” are also used to mean “communicatively coupled with”, possibly via one or more intermediary devices.

Although the following description uses terms “first,” “second,” etc. to describe various elements, these elements should not be limited by the terms. These terms are only used to distinguish one element from another. For example, a first exterior surface could be termed a second exterior surface and, similarly, a second exterior surface could be termed a first exterior surface, without departing from the scope of the various described examples. The first exterior surface and the second exterior surface can both be exterior surfaces and, in some cases, can be separate and different exterior surfaces.

In addition, throughout the specification, the meaning of “a”, “an”, and “the” includes plural references, and the meaning of “in” includes “in” and “on”.

Although some of the various embodiments presented herein constitute a single combination of inventive elements, it should be appreciated that the inventive subject matter is considered to include all possible combinations of the disclosed elements. As such, if one embodiment comprises elements A, B, and C, and another embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly discussed herein. Further, the transitional term “comprising” means to have as parts or members, or to be those parts or members. As used herein, the transitional term “comprising” is inclusive or open-ended and does not exclude additional, unrecited elements or method steps.

Throughout the following disclosure, numerous references may be made regarding servers, services, interfaces, engines, modules, clients, peers, portals, platforms, or other systems formed from computing devices. It should be appreciated that the use of such terms is deemed to represent one or more computing devices having at least one processor (e.g., ASIC, FPGA, PLD, DSP, x86, ARM, RISC-V, ColdFire, GPU, multi-core processors, etc.) configured to execute software instructions stored on a computer readable tangible, non-transitory medium (e.g., hard drive, solid state drive, RAM, flash, ROM, etc.). For example, a server can include one or more computers operating as a web server, database server, or other type of computer server in a manner to fulfill described roles, responsibilities, or functions. One should further appreciate the disclosed computer-based algorithms, processes, methods, or other types of instruction sets can be embodied as a computer program product comprising a non-transitory, tangible computer readable medium storing the instructions that cause a processor to execute the disclosed steps. The various servers, systems, databases, or interfaces can exchange data using standardized protocols or algorithms, possibly based on HTTP, HTTPS, AES, public-private key exchanges, web service APIs, known financial transaction protocols, or other electronic information exchanging methods. Data exchanges can be conducted over a packet-switched network, a circuit-switched network, the Internet, LAN, WAN, VPN, or other type of network.

As used in the description herein and throughout the claims that follow, when a system, engine, server, device, module, or other computing element is described as being configured to perform or execute functions on data in a memory, the meaning of “configured to” or “programmed to” is defined as one or more processors or cores of the computing element being programmed by a set of software instructions stored in the memory of the computing element to execute the set of functions on target data or data objects stored in the memory.

It should be noted that any language directed to a computer should be read to include any suitable combination of computing devices or network platforms, including servers, interfaces, systems, databases, agents, peers, engines, controllers, modules, or other types of computing devices operating individually or collectively. One should appreciate the computing devices comprise a processor configured to execute software instructions stored on a tangible, non-transitory computer readable storage medium (e.g., hard drive, FPGA, PLA, solid state drive, RAM, flash, ROM, etc.). The software instructions configure or program the computing device to provide the roles, responsibilities, or other functionality as discussed below with respect to the disclosed apparatus. Further, the disclosed technologies can be embodied as a computer program product that includes a non-transitory computer readable medium storing the software instructions that causes a processor to execute the disclosed steps associated with implementations of computer-based algorithms, processes, methods, or other instructions. In some embodiments, the various servers, systems, databases, or interfaces exchange data using standardized protocols or algorithms, possibly based on HTTP, HTTPS, AES, public-private key exchanges, web service APIs, known financial transaction protocols, or other electronic information exchanging methods. Data exchanges among devices can be conducted over a packet-switched network, the Internet, LAN, WAN, VPN, or other type of packet switched network; a circuit switched network; cell switched network; or other type of network.

Conventional LiDAR systems known in the art may be rather bulky and protruding when mounted on top of a vehicle, making them unattractive in terms of aerodynamics and vehicle styling, and impractical for manufacturing for mass deployment. Compact LiDAR systems are known in the art, but the compact design may compromise the size of the receiving aperture and therefore may negatively impact long distance detection performance. Embodiments of the invention disclosed herein propose novel designs optimized with overall vehicle aerodynamics in mind, so that the LiDAR system is compact and may be integrated seamlessly into the top portion of the vehicle.

FIG. 1 illustrates one or more exemplary LiDAR systems 110 disposed or included in a motor vehicle 100. Motor vehicle 100 can be a vehicle having any automated level. For example, motor vehicle 100 can be a partially automated vehicle, a highly automated vehicle, a fully automated vehicle, or a driverless vehicle. A partially automated vehicle can perform some driving functions without a human driver's intervention. For example, a partially automated vehicle can perform blind-spot monitoring, lane keeping and/or lane changing operations, automated emergency braking, smart cruising and/or traffic following, or the like. Certain operations of a partially automated vehicle may be limited to specific applications or driving scenarios (e.g., limited to only freeway driving). A highly automated vehicle can perform all operations of a partially automated vehicle but with less limitations. A highly automated vehicle can also detect its own limits in operating the vehicle and ask the driver to take over the control of the vehicle when necessary. A fully automated vehicle can perform all vehicle operations without a driver's intervention but can also detect its own limits and ask the driver to take over when necessary. A driverless vehicle can operate on its own without any driver intervention.

In typical configurations, motor vehicle 100 comprises one or more LiDAR systems 110 and 120A-F. Each of LiDAR systems 110 and 120A-F can be a scanning-based LiDAR system and/or a non-scanning LiDAR system (e.g., a flash LiDAR). A scanning-based LiDAR system scans one or more light beams in one or more directions (e.g., horizontal and vertical directions) to detect objects in a field-of-view (FOV). A non-scanning based LiDAR system transmits laser light to illuminate an FOV without scanning. For example, a flash LiDAR is a type of non-scanning based LiDAR system. A flash LiDAR can transmit laser light to simultaneously illuminate an FOV using a single light pulse or light shot.

A LiDAR system is often an essential sensor of a vehicle that is at least partially automated. In one embodiment, as shown in FIG. 1 , motor vehicle 100 may include a single LiDAR system 110 (e.g., without LiDAR systems 120A-H) disposed at the highest position of the vehicle (e.g., at the vehicle roof). Disposing LiDAR system 110 at the vehicle roof facilitates a 360-degree scanning around vehicle 100. In some other embodiments, motor vehicle 100 can include multiple LiDAR systems, including two or more of systems 110 and/or 120A-H. As shown in FIG. 1 , in one embodiment, multiple LiDAR systems 110 and/or 120A-H are attached to vehicle 100 at various locations of the vehicle. For example, LiDAR system 120A is attached to vehicle 100 at the front right corner; LiDAR system 120B is attached to vehicle 100 at the front center; LiDAR system 120C is attached to vehicle 100 at the front left corner; LiDAR system 120D is attached to vehicle 100 at the right-side rear view mirror; LiDAR system 120E is attached to vehicle 100 at the left-side rear view mirror; LiDAR system 120F is attached to vehicle 100 at the back center; LiDAR system 120G is attached to vehicle 100 at the right-side rear corner; and/or LiDAR system 120H is attached to vehicle 100 at the left-side rear corner of the vehicle 100. In some embodiments, LiDAR systems 110 and 120A-H are independent LiDAR systems having their own respective laser sources, control electronics, transmitters, receivers, and/or steering mechanisms. In other embodiments, some of LiDAR systems 110 and 120A-H can share one or more components, thereby forming a distributed sensor system. In one example, optical fibers are used to deliver laser light from a centralized laser source to all LiDAR systems. It is understood that one or more LiDAR systems can be distributed and attached to a vehicle in any desired manner and FIG. 1 only illustrates one embodiment. As another example, LiDAR systems 120D and 120E may be attached to the B-pillars of vehicle 100 instead of the rear-view mirrors. As another example, LiDAR system 120B may be attached to the windshield of vehicle 100 instead of the front bumper.

FIG. 2 is a block diagram 200 illustrating interactions between vehicle onboard LiDAR system(s) 210 and multiple other systems including a vehicle perception and planning system 220. LiDAR system(s) 210 can be mounted on or integrated to a vehicle. LiDAR system(s) 210 include sensor(s) that scan laser light to the surrounding environment to measure the distance, angle, and/or velocity of objects. Based on the scattered light that returned to LiDAR system(s) 210, it can generate sensor data (e.g., image data or 3D point cloud data) representing the perceived external environment.

LiDAR system(s) 210 can include one or more of short-range LiDAR sensors, medium-range LiDAR sensors, and long-range LiDAR sensors. A short-range LiDAR sensor measures objects located up to about 20-40 meters from the LiDAR sensor. Short-range LiDAR sensors can be used for, e.g., monitoring nearby moving objects (e.g., pedestrians crossing street in a school zone), parking assistance applications, or the like. A medium-range LiDAR sensor measures objects located up to about 100-150 meters from the LiDAR sensor. Medium-range LiDAR sensors can be used for, e.g., monitoring road intersections, assistance for merging onto or leaving a freeway, or the like. A long-range LiDAR sensor measures objects located up to about 150-300 meters. Long-range LiDAR sensors are typically used when a vehicle is travelling at high speed (e.g., on a freeway), such that the vehicle's control systems may only have a few seconds (e.g., 6-8 seconds) to respond to any situations detected by the LiDAR sensor. As shown in FIG. 2 , in one embodiment, the LiDAR sensor data can be provided to vehicle perception and planning system 220 via a communication path 213 for further processing and controlling the vehicle operations. Communication path 213 can be any wired or wireless communication links that can transfer data.

With reference still to FIG. 2 , in some embodiments, other vehicle onboard sensor(s) 230 are used to provide additional sensor data separately or together with LiDAR system(s) 210. Other vehicle onboard sensors 230 may include, for example, one or more camera(s) 232, one or more radar(s) 234, one or more ultrasonic sensor(s) 236, and/or other sensor(s) 238. Camera(s) 232 can take images and/or videos of the external environment of a vehicle. Camera(s) 232 can take, for example, high-definition (HD) videos having millions of pixels in each frame. A camera produces monochrome or color images and videos. Color information may be important in interpreting data for some situations (e.g., interpreting images of traffic lights). Color information may not be available from other sensors such as LiDAR or radar sensors. Camera(s) 232 can include one or more of narrow-focus cameras, wider-focus cameras, side-facing cameras, infrared cameras, fisheye cameras, or the like. The image and/or video data generated by camera(s) 232 can also be provided to vehicle perception and planning system 220 via communication path 233 for further processing and controlling the vehicle operations. Communication path 233 can be any wired or wireless communication links that can transfer data.

Other vehicle onboard sensor(s) 230 can also include radar sensor(s) 234. Radar sensor(s) 234 use radio waves to determine the range, angle, and velocity of objects. Radar sensor(s) 234 produce electromagnetic waves in the radio or microwave spectrum. The electromagnetic waves reflect off an object and some of the reflected waves return to the radar sensor, thereby providing information about the object's position and velocity. Radar sensor(s) 234 can include one or more of short-range radar(s), medium-range radar(s), and long-range radar(s). A short-range radar measures objects located at about 0.1-30 meters from the radar. A short-range radar is useful in detecting objects located nearby the vehicle, such as other vehicles, buildings, walls, pedestrians, bicyclists, etc. A short-range radar can be used to detect a blind spot, assist in lane changing, provide rear-end collision warning, assist in parking, provide emergency braking, or the like. A medium-range radar measures objects located at about 30-80 meters from the radar. A long-range radar measures objects located at about 80-200 meters. Medium- and/or long-range radars can be useful in, for example, traffic following, adaptive cruise control, and/or highway automatic braking. Sensor data generated by radar sensor(s) 234 can also be provided to vehicle perception and planning system 220 via communication path 233 for further processing and controlling the vehicle operations.

Other vehicle onboard sensor(s) 230 can also include ultrasonic sensor(s) 236. Ultrasonic sensor(s) 236 use acoustic waves or pulses to measure object locations external to a vehicle. The acoustic waves generated by ultrasonic sensor(s) 236 are transmitted to the surrounding environment. At least some of the transmitted waves are reflected off an object and return to the ultrasonic sensor(s) 236. Based on the return signals, a distance of the object can be calculated. Ultrasonic sensor(s) 236 can be useful in, for example, checking blind spots, identifying parking spots, providing lane changing assistance into traffic, or the like. Sensor data generated by ultrasonic sensor(s) 236 can also be provided to vehicle perception and planning system 220 via communication path 233 for further processing and controlling the vehicle operations.

In some embodiments, one or more other sensor(s) 238 may be attached in a vehicle and may also generate sensor data. Other sensor(s) 238 may include, for example, global positioning systems (GPS), inertial measurement units (IMU), or the like. Sensor data generated by other sensor(s) 238 can also be provided to vehicle perception and planning system 220 via communication path 233 for further processing and controlling the vehicle operations. It is understood that communication path 233 may include one or more communication links to transfer data between the various sensor(s) 230 and vehicle perception and planning system 220.

In some embodiments, as shown in FIG. 2 , sensor data from other vehicle onboard sensor(s) 230 can be provided to vehicle onboard LiDAR system(s) 210 via communication path 231. LiDAR system(s) 210 may process the sensor data from other vehicle onboard sensor(s) 230. For example, sensor data from camera(s) 232, radar sensor(s) 234, ultrasonic sensor(s) 236, and/or other sensor(s) 238 may be correlated or fused with sensor data LiDAR system(s) 210, thereby at least partially offloading the sensor fusion process performed by vehicle perception and planning system 220. It is understood that other configurations may also be implemented for transmitting and processing sensor data from the various sensors (e.g., data can be transmitted to a cloud service for processing and then the processing results can be transmitted back to the vehicle perception and planning system 220).

With reference still to FIG. 2 , in some embodiments, sensors onboard other vehicle(s) 250 are used to provide additional sensor data separately or together with LiDAR system(s) 210. For example, two or more nearby vehicles may have their own respective LiDAR sensor(s), camera(s), radar sensor(s), ultrasonic sensor(s), etc. Nearby vehicles can communicate and share sensor data with one another. Communications between vehicles are also referred to as V2V (vehicle to vehicle) communications. For example, as shown in FIG. 2 , sensor data generated by other vehicle(s) 250 can be communicated to vehicle perception and planning system 220 and/or vehicle onboard LiDAR system(s) 210, via communication path 253 and/or communication path 251, respectively. Communication paths 253 and 251 can be any wired or wireless communication links that can transfer data.

Sharing sensor data facilitates a better perception of the environment external to the vehicles. For instance, a first vehicle may not sense a pedestrian that is a behind a second vehicle but is approaching the first vehicle. The second vehicle may share the sensor data related to this pedestrian with the first vehicle such that the first vehicle can have additional reaction time to avoid collision with the pedestrian. In some embodiments, similar to data generated by sensor(s) 230, data generated by sensors onboard other vehicle(s) 250 may be correlated or fused with sensor data generated by LiDAR system(s) 210, thereby at least partially offloading the sensor fusion process performed by vehicle perception and planning system 220.

In some embodiments, intelligent infrastructure system(s) 240 are used to provide sensor data separately or together with LiDAR system(s) 210. Certain infrastructures may be configured to communicate with a vehicle to convey information and vice versa. Communications between a vehicle and infrastructures are referred to as V2I (vehicle to infrastructure) communications. For example, intelligent infrastructure system(s) 240 may include an intelligent traffic light that can convey its status to an approaching vehicle in a message such as “changing to yellow in 5 seconds.” Intelligent infrastructure system(s) 240 may also include its own LiDAR system mounted near an intersection such that it can convey traffic monitoring information to a vehicle. For example, a left-turning vehicle at an intersection may not have sufficient sensing capabilities because some of its own sensors may be blocked by vehicular traffic travelling in the opposite direction. In such a situation, sensors of intelligent infrastructure system(s) 240 can provide useful, and sometimes vital, data to the left-turning vehicle. Such data may include, for example, traffic conditions, information of objects in the direction the vehicle is turning to, traffic light status and predictions, or the like. These sensor data generated by intelligent infrastructure system(s) 240 can be provided to vehicle perception and planning system 220 and/or vehicle onboard LiDAR system(s) 210, via communication paths 243 and/or 241, respectively.

Communication paths 243 and/or 241 can include any wired or wireless communication links that can transfer data. For example, sensor data from intelligent infrastructure system(s) 240 may be transmitted to LiDAR system(s) 210 and correlated or fused with sensor data generated by LiDAR system(s) 210, thereby at least partially offloading the sensor fusion process performed by vehicle perception and planning system 220. V2V and V2I communications described above are examples of vehicle-to-X (V2X) communications, where the “X” represents any other devices, systems, sensors, infrastructure, or the like that can share data with a vehicle.

With reference still to FIG. 2 , via various communication paths, vehicle perception and planning system 220 receives sensor data from one or more of LiDAR system(s) 210, other vehicle onboard sensor(s) 230, other vehicle(s) 250, and/or intelligent infrastructure system(s) 240. In some embodiments, distinct types of sensor data are correlated and/or integrated by a sensor fusion sub-system 222. For example, sensor fusion sub-system 222 can generate a 360-degree model using multiple images or videos captured by multiple cameras disposed at various positions of the vehicle. Sensor fusion sub-system 222 obtains sensor data from diverse types of sensors and uses the combined data to perceive the environment more accurately. For example, a vehicle onboard camera 232 may not capture a clear image because it is facing the sun or a light source (e.g., another vehicle's headlight during nighttime) directly. A LiDAR system 210 may not be affected as much and therefore sensor fusion sub-system 222 can combine sensor data provided by both camera 232 and LiDAR system 210, and use the sensor data provided by LiDAR system 210 to compensate the unclear image captured by camera 232. As another example, in a rainy or foggy weather, a radar sensor 234 may work better than a camera 232 or a LiDAR system 210. Accordingly, sensor fusion sub-system 222 may use sensor data provided by the radar sensor 234 to compensate for the sensor data provided by camera 232 or LiDAR system 210.

In other examples, sensor data generated by other vehicle onboard sensor(s) 230 may have a lower resolution (e.g., radar sensor data) and thus may need to be correlated and confirmed by LiDAR system(s) 210, which usually has a higher resolution. For example, a sewage cover (also referred to as a utility access hole cover) may be detected by radar sensor 234 as an object towards which a vehicle is approaching. Due to the low-resolution nature of radar sensor 234, vehicle perception and planning system 220 may not be able to determine whether the object is an obstacle that the vehicle needs to avoid. High-resolution sensor data generated by LiDAR system(s) 210 thus can be used to correlated and confirm that the object is a sewage cover and causes no harm to the vehicle.

Vehicle perception and planning system 220 further comprises an object classifier 223. Using raw sensor data and/or correlated/fused data provided by sensor fusion sub-system 222, object classifier 223 can detect and classify the objects and estimate the positions of the objects. In some embodiments, object classifier 233 can use machine-learning based techniques to detect and classify objects. Examples of the machine-learning based techniques include utilizing algorithms such as region-based convolutional neural networks (R-CNN), Fast R-CNN, Faster R-CNN, histogram of oriented gradients (HOG), region-based fully convolutional network (R-FCN), single shot detector (SSD), spatial pyramid pooling (SPP-net), and/or You Only Look Once (Yolo).

Vehicle perception and planning system 220 further comprises a road detection sub-system 224. Road detection sub-system 224 localizes the road and identifies objects and/or markings on the road. For example, based on raw or fused sensor data provided by radar sensor(s) 234, camera(s) 232, and/or LiDAR system(s) 210, road detection sub-system 224 can build a 3D model of the road based on machine-learning techniques (e.g., pattern recognition algorithms for identifying lanes). Using the 3D model of the road, road detection sub-system 224 can identify objects (e.g., obstacles or debris on the road) and/or markings on the road (e.g., lane lines, turning marks, crosswalk marks, or the like).

Vehicle perception and planning system 220 further comprises a localization and vehicle posture sub-system 225. Based on raw or fused sensor data, localization and vehicle posture sub-system 225 can determine position of the vehicle and the vehicle's posture. For example, using sensor data from LiDAR system(s) 210, camera(s) 232, and/or GPS data, localization and vehicle posture sub-system 225 can determine an accurate position of the vehicle on the road and the vehicle's six degrees of freedom (e.g., whether the vehicle is moving forward or backward, up or down, and left or right). In some embodiments, high-definition (HD) maps are used for vehicle localization. HD maps can provide highly detailed, three-dimensional, computerized maps that pinpoint a vehicle's location. For instance, using the HD maps, localization and vehicle posture sub-system 225 can determine precisely the vehicle's current position (e.g., which lane of the road the vehicle is currently in, how close it is to a curb or a sidewalk) and predict the vehicle's future positions.

Vehicle perception and planning system 220 further comprises obstacle predictor 226. Objects identified by object classifier 223 can be stationary (e.g., a light pole, a road sign) or dynamic (e.g., a moving pedestrian, bicycle, another car). For moving objects, predicting their moving path or future positions can be important to avoid collision. Obstacle predictor 226 can predict an obstacle trajectory and/or warn the driver or the vehicle planning sub-system 228 about a potential collision. For example, if there is a high likelihood that the obstacle's trajectory intersects with the vehicle's current moving path, obstacle predictor 226 can generate such a warning. Obstacle predictor 226 can use a variety of techniques for making such a prediction. Such techniques include, for example, constant velocity or acceleration models, constant turn rate and velocity/acceleration models, Kalman Filter and Extended Kalman Filter based models, recurrent neural network (RNN) based models, long short-term memory (LSTM) neural network based models, encoder-decoder RNN models, or the like.

With reference still to FIG. 2 , in some embodiments, vehicle perception and planning system 220 further comprises vehicle planning sub-system 228. Vehicle planning sub-system 228 can include a route planner, a driving behaviors planner, and a motion planner. The route planner can plan the route of a vehicle based on the vehicle's current location data, target location data, traffic information, etc. The driving behavior planner adjusts the timing and planned movement based on how other objects might move, using the obstacle prediction results provided by obstacle predictor 226. The motion planner determines the specific operations the vehicle needs to follow. The planning results are then communicated to vehicle control system 280 via vehicle interface 270. The communication can be performed through communication paths 223 and 271, which include any wired or wireless communication links that can transfer data.

Vehicle control system 280 controls the vehicle's steering mechanism, throttle, brake, etc., to operate the vehicle according to the planned route and movement. Vehicle perception and planning system 220 may further comprise a user interface 260, which provides a user (e.g., a driver) access to vehicle control system 280 to, for example, override or take over control of the vehicle when necessary. User interface 260 can communicate with vehicle perception and planning system 220, for example, to obtain and display raw or fused sensor data, identified objects, vehicle's location/posture, etc. These displayed data can help a user to better operate the vehicle. User interface 260 can communicate with vehicle perception and planning system 220 and/or vehicle control system 280 via communication paths 221 and 261 respectively, which include any wired or wireless communication links that can transfer data. It is understood that the various systems, sensors, communication links, and interfaces in FIG. 2 can be configured in any desired manner and not limited to the configuration shown in FIG. 2 .

FIG. 3 is a block diagram illustrating an exemplary LiDAR system 300. LiDAR system 300 can be used to implement LiDAR system 110, 120A-H, and/or 210 shown in FIGS. 1 and 2 . In one embodiment, LiDAR system 300 comprises a laser source 310, a transmitter 320, an optical receiver and light detector 330, a steering mechanism or system 340, and a control circuitry 350. These components are coupled together using communications paths 312, 314, 322, 332, 343, 352, and 362. These communications paths include communication links (wired or wireless, bidirectional or unidirectional) among the various LiDAR system components, but need not be physical components themselves. While the communications paths can be implemented by one or more electrical wires, buses, or optical fibers, the communication paths can also be wireless channels or free-space optical paths so that no physical communication medium is present. For example, in one embodiment of LiDAR system 300, communication path 314 between laser source 310 and transmitter 320 may be implemented using one or more optical fibers. Communication paths 332 and 352 may represent optical paths implemented using free space optical components and/or optical fibers. And communication paths 312, 322, 342, and 362 may be implemented using one or more electrical wires that carry electrical signals. The communications paths can also include one or more of the above types of communication mediums (e.g., they can include an optical fiber and a free-space optical component, or include one or more optical fibers and one or more electrical wires).

LiDAR system 300 can also include other components not depicted in FIG. 3 , such as power buses, power supplies, LED indicators, switches, etc. Additionally, other communication connections among components may be present, such as a direct connection between light source 310 and optical receiver and light detector 330 to provide a reference signal so that the time from when a light pulse is transmitted until a return light pulse is detected can be accurately measured.

Laser source 310 outputs laser light for illuminating objects in a field of view (FOV). Laser source 310 can be, for example, a semiconductor-based laser (e.g., a diode laser) and/or a fiber-based laser. A semiconductor-based laser can be, for example, an edge emitting laser (EEL), a vertical cavity surface emitting laser (VCSEL), or the like. A fiber-based laser is a laser in which the active gain medium is an optical fiber doped with rare-earth elements such as erbium, ytterbium, neodymium, dysprosium, praseodymium, thulium and/or holmium. In some embodiments, a fiber laser is based on double-clad fibers, in which the gain medium forms the core of the fiber surrounded by two layers of cladding. The double-clad fiber allows the core to be pumped with a high-power beam, thereby enabling the laser source to be a high power fiber laser source.

In some embodiments, laser source 310 comprises a master oscillator (also referred to as a seed laser) and power amplifier (MOPA). The power amplifier amplifies the output power of the seed laser. The power amplifier can be a fiber amplifier, a bulk amplifier, or a semiconductor optical amplifier. The seed laser can be a diode laser (e.g., a Fabry-Perot cavity laser, a distributed feedback laser), a solid-state bulk laser, or a tunable external-cavity diode laser. In some embodiments, laser source 310 can be an optically pumped microchip laser. Microchip lasers are alignment-free monolithic solid-state lasers where the laser crystal is directly contacted with the end mirrors of the laser resonator. A microchip laser is typically pumped with a laser diode (directly or using a fiber) to obtain the desired output power. A microchip laser can be based on neodymium-doped yttrium aluminum garnet (Y₃Al₅O₁₂) laser crystals (i.e., Nd:YAG), or neodymium-doped vanadate (i.e., ND:YVO₄) laser crystals.

FIG. 4 is a block diagram illustrating an exemplary fiber-based laser source 400 having a seed laser and one or more pumps (e.g., laser diodes) for pumping desired output power. Fiber-based laser source 400 is an example of laser source 310 depicted in FIG. 3 . In some embodiments, fiber-based laser source 400 comprises a seed laser 402 to generate initial light pulses of one or more wavelengths (e.g., 1550 nm), which are provided to a wavelength-division multiplexor (WDM) 404 via an optical fiber 403. Fiber-based laser source 400 further comprises a pump 406 for providing laser power (e.g., of a different wavelength, such as 980 nm) to WDM 404 via an optical fiber 405. WDM 404 multiplexes the light pulses provided by seed laser 402 and the laser power provided by pump 406 onto a single optical fiber 407. The output of WDM 404 can then be provided to one or more pre-amplifier(s) 408 via optical fiber 407. Pre-amplifier(s) 408 can be optical amplifier(s) that amplify optical signals (e.g., with about 20-30 dB gain). In some embodiments, pre-amplifier(s) 408 are low noise amplifiers. Pre-amplifier(s) 408 output to a combiner 410 via an optical fiber 409. Combiner 410 combines the output laser light of pre-amplifier(s) 408 with the laser power provided by pump 412 via an optical fiber 411. Combiner 410 can combine optical signals having the same wavelength or different wavelengths. One example of a combiner is a WDM. Combiner 410 provides pulses via optical fiber 413 to a booster amplifier 414, which produces output light pulses via optical fiber 415. The booster amplifier 414 provides further amplification of the optical signals. The outputted light pulses can then be transmitted to transmitter 320 and/or steering mechanism 340 (shown in FIG. 3 ). It is understood that FIG. 4 illustrates one exemplary configuration of fiber-based laser source 400. Laser source 400 can have many other configurations using different combinations of one or more components shown in FIG. 4 and/or other components not shown in FIG. 4 (e.g., other components such as power supplies, lens, filters, splitters, combiners, etc.).

In some variations, fiber-based laser source 400 can be controlled (e.g., by control circuitry 350) to produce pulses of different amplitudes based on the fiber gain profile of the fiber used in fiber-based laser source 400. Communication path 312 couples fiber-based laser source 400 to control circuitry 350 (shown in FIG. 3 ) so that components of fiber-based laser source 400 can be controlled by or otherwise communicate with control circuitry 350. Alternatively, fiber-based laser source 400 may include its own dedicated controller. Instead of control circuitry 350 communicating directly with components of fiber-based laser source 400, a dedicated controller of fiber-based laser source 400 communicates with control circuitry 350 and controls and/or communicates with the components of fiber-based light source 400. Fiber-based light source 400 can also include other components not shown, such as one or more power connectors, power supplies, and/or power lines.

Referencing FIG. 3 , typical operating wavelengths of laser source 310 comprise, for example, about 850 nm, about 905 nm, about 940 nm, about 1064 nm, and about 1550 nm. The upper limit of maximum usable laser power is set by the U.S. FDA (U.S. Food and Drug Administration) regulations. The optical power limit at 1550 nm wavelength is much higher than those of the other aforementioned wavelengths. Further, at 1550 nm, the optical power loss in a fiber is low. There characteristics of the 1550 nm wavelength make it more beneficial for long-range LiDAR applications. The amount of optical power output from laser source 310 can be characterized by its peak power, average power, and the pulse energy. The peak power is the ratio of pulse energy to the width of the pulse (e.g., full width at half maximum or FWHM). Thus, a smaller pulse width can provide a larger peak power for a fixed amount of pulse energy. A pulse width can be in the range of nanosecond or picosecond. The average power is the product of the energy of the pulse and the pulse repetition rate (PRR). As described in more detail below, the PRR represents the frequency of the pulsed laser light. The PRR typically corresponds to the maximum range that a LiDAR system can measure. Laser source 310 can be configured to produce pulses at high PRR to meet the desired number of data points in a point cloud generated by the LiDAR system. Laser source 310 can also be configured to produce pulses at medium or low PRR to meet the desired maximum detection distance. Wall plug efficiency (WPE) is another factor to evaluate the total power consumption, which may be a key indicator in evaluating the laser efficiency. For example, as shown in FIG. 1 , multiple LiDAR systems may be attached to a vehicle, which may be an electrical-powered vehicle or a vehicle otherwise having limited fuel or battery power supply. Therefore, high WPE and intelligent ways to use laser power are often among the important considerations when selecting and configuring laser source 310 and/or designing laser delivery systems for vehicle-mounted LiDAR applications.

It is understood that the above descriptions provide non-limiting examples of a laser source 310. Laser source 310 can be configured to include many other types of light sources (e.g., laser diodes, short-cavity fiber lasers, solid-state lasers, and/or tunable external cavity diode lasers) that are configured to generate one or more light signals at various wavelengths. In some examples, light source 310 comprises amplifiers (e.g., pre-amplifiers and/or booster amplifiers), which can be a doped optical fiber amplifier, a solid-state bulk amplifier, and/or a semiconductor optical amplifier. The amplifiers are configured to receive and amplify light signals with desired gains.

With reference back to FIG. 3 , LiDAR system 300 further comprises a transmitter 320. Laser source 310 provides laser light (e.g., in the form of a laser beam) to transmitter 320. The laser light provided by laser source 310 can be amplified laser light with a predetermined or controlled wavelength, pulse repetition rate, and/or power level. Transmitter 320 receives the laser light from laser source 310 and transmits the laser light to steering mechanism 340 with low divergence. In some embodiments, transmitter 320 can include, for example, optical components (e.g., lens, fibers, mirrors, etc.) for transmitting laser beams to a field-of-view (FOV) directly or via steering mechanism 340. While FIG. 3 illustrates transmitter 320 and steering mechanism 340 as separate components, they may be combined or integrated as one system in some embodiments. Steering mechanism 340 is described in more detail below.

Laser beams provided by laser source 310 may diverge as they travel to transmitter 320. Therefore, transmitter 320 often comprises a collimating lens configured to collect the diverging laser beams and produce more parallel optical beams with reduced or minimum divergence. The collimated optical beams can then be further directed through various optics such as mirrors and lens. A collimating lens may be, for example, a single plano-convex lens or a lens group. The collimating lens can be configured to achieve any desired properties such as the beam diameter, divergence, numerical aperture, focal length, or the like. A beam propagation ratio or beam quality factor (also referred to as the M² factor) is used for measurement of laser beam quality. In many LiDAR applications, it is important to have good laser beam quality in the generated transmitting laser beam. The M² factor represents a degree of variation of a beam from an ideal Gaussian beam. Thus, the M² factor reflects how well a collimated laser beam can be focused on a small spot, or how well a divergent laser beam can be collimated. Therefore, laser source 310 and/or transmitter 320 can be configured to meet, for example, a scan resolution requirement while maintaining the desired M² factor.

One or more of the light beams provided by transmitter 320 are scanned by steering mechanism 340 to a FOV. Steering mechanism 340 scans light beams in multiple dimensions (e.g., in both the horizontal and vertical dimension) to facilitate LiDAR system 300 to map the environment by generating a 3D point cloud. Steering mechanism 340 will be described in more detail below. The laser light scanned to an FOV may be scattered or reflected by an object in the FOV. At least a portion of the scattered or reflected light returns to LiDAR system 300. FIG. 3 further illustrates an optical receiver and light detector 330 configured to receive the return light. Optical receiver and light detector 330 comprise an optical receiver that is configured to collect the return light from the FOV. The optical receiver can include optics (e.g., lens, fibers, mirrors, etc.) for receiving, redirecting, focus, amplifying, and/or filtering return light from the FOV. For example, the optical receiver often includes a collection lens (e.g., a single plano-convex lens or a lens group) to collect and/or focus the collected return light onto a light detector.

A light detector detects the return light focused by the optical receiver and generates current and/or voltage signals proportional to the incident intensity of the return light. Based on such current and/or voltage signals, the depth information of the object in the FOV can be derived. One exemplary method for deriving such depth information is based on the direct TOF (time of flight), which is described in more detail below. A light detector may be characterized by its detection sensitivity, quantum efficiency, detector bandwidth, linearity, signal to noise ratio (SNR), overload resistance, interference immunity, etc. Based on the applications, the light detector can be configured or customized to have any desired characteristics. For example, optical receiver and light detector 330 can be configured such that the light detector has a large dynamic range while having a good linearity. The light detector linearity indicates the detector's capability of maintaining linear relationship between input optical signal power and the detector's output. A detector having good linearity can maintain a linear relationship over a large dynamic input optical signal range.

To achieve desired detector characteristics, configurations or customizations can be made to the light detector's structure and/or the detector's material system. Various detector structure can be used for a light detector. For example, a light detector structure can be a PIN based structure, which has a undoped intrinsic semiconductor region (i.e., an “i” region) between a p-type semiconductor and an n-type semiconductor region. Other light detector structures comprise, for example, a APD (avalanche photodiode) based structure, a PMT (photomultiplier tube) based structure, a SiPM (Silicon photomultiplier) based structure, a SPAD (single-photon avalanche diode) base structure, and/or quantum wires. For material systems used in a light detector, Si, InGaAs, and/or Si/Ge based materials can be used. It is understood that many other detector structures and/or material systems can be used in optical receiver and light detector 330.

A light detector (e.g., an APD based detector) may have an internal gain such that the input signal is amplified when generating an output signal. However, noise may also be amplified due to the light detector's internal gain. Common types of noise include signal shot noise, dark current shot noise, thermal noise, and amplifier noise. In some embodiments, optical receiver and light detector 330 may include a pre-amplifier that is a low noise amplifier (LNA). In some embodiments, the pre-amplifier may also include a TIA (transimpedance) amplifier, which converts a current signal to a voltage signal. For a linear detector system, input equivalent noise or noise equivalent power (NEP) measures how sensitive the light detector is to weak signals. Therefore, they can be used as indicators of the overall system performance. For example, the NEP of a light detector specifies the power of the weakest signal that can be detected and therefore it in turn specifies the maximum range of a LiDAR system. It is understood that various light detector optimization techniques can be used to meet the requirement of LiDAR system 300. Such optimization techniques may include selecting different detector structures, optics (e.g., lens, fibers, mirrors, etc. for receiving or redirecting return light from the FoV), materials, and/or implement signal processing techniques (e.g., filtering, noise reduction, amplification, or the like). For example, in addition to or instead of using direct detection of return signals (e.g., by using TOF), coherent detection can also be used for a light detector. Coherent detection allows for detecting amplitude and phase information of the received light by interfering the received light with a local oscillator. Coherent detection can improve detection sensitivity and noise immunity.

FIG. 3 further illustrates that LiDAR system 300 comprises steering mechanism 340. As described above, steering mechanism 340 directs light beams from transmitter 320 to scan an FOV in multiple dimensions. A steering mechanism is referred to as a raster mechanism or a scanning mechanism. Scanning light beams in multiple directions (e.g., in both the horizontal and vertical directions) facilitates a LiDAR system to map the environment by generating an image or a 3D point cloud. A steering mechanism can be based on mechanical scanning and/or solid-state scanning. Mechanical scanning uses one or several single-point transceivers plus a two-dimensional mechanical scanner. Rotating mirrors, e.g., polygon mirrors, oscillating mirrors, spinning prisms, spinning tilt mirrors, or a combination thereof may be used to steer the laser beam or physically rotate the LiDAR transmitter and receiver (collectively referred to as transceiver) to scan the laser beam. Solid-state scanning directs the laser beam to various positions through the FOV without mechanically moving any macroscopic components such as the transceiver. Solid-state scanning mechanisms include, for example, optical phased arrays-based steering and flash LiDAR-based steering. In some embodiments, because solid-state scanning mechanisms do not physically move macroscopic components, the steering performed by a solid-state scanning mechanism may be referred to as effective steering. A LiDAR system using solid-state scanning may also be referred to as a non-mechanical scanning or simply non-scanning LiDAR system (a flash LiDAR system is an exemplary non-scanning LiDAR system). Other non-mechanical methods include, for example, tuning the wavelength of a laser beam combined with a refraction effect, or a reconfigurable grating/phase array. A single device can be used to achieve two-dimensional rastering or two devices combined to realize two-dimensional rastering. The second way uses a linear array or a large number of single-point transceivers plus a one-dimensional mechanical scanner. This may be achieved by mounting the whole transceiver array on a spinning platform to achieve a 360-degree horizontal FoV, or a static transceiver array combined with polygon mirrors, oscillating mirrors, spinning prisms, or a spinning tilt mirror surface to achieve a forward looking horizontal FoV. Yet another method includes using a two-dimensional transceiver to form an image directly, and using a stitching or micro shift method to improve resolution or FoV. Mechanical scanning methods have been demonstrated to be suitable for robustness and volume production for automotive applications.

Steering mechanism 340 can be used with the transceiver (e.g., transmitter 320 and optical receiver and light detector 330) to scan the FOV for generating an image or a 3D point cloud. As an example, to implement steering mechanism 340, a two-dimensional mechanical scanner can be used with a single-point or several single-point transceivers. A single-point transceiver transmits a single light beam or a small number of light beams (e.g., 2-8 beams) to the steering mechanism. A two-dimensional mechanical steering mechanism comprises, for example, polygon mirror(s), oscillating mirror(s), rotating prism(s), rotating tilt mirror surface(s), or a combination thereof. In some embodiments, steering mechanism 340 may include non-mechanical steering mechanism(s) such as solid-state steering mechanism(s). For example, steering mechanism 340 can be based on tuning wavelength of the laser light combined with refraction effect, and/or based on reconfigurable grating/phase array. In some embodiments, steering mechanism 340 can use a single scanning device to achieve two-dimensional scanning or two devices combined to realize two-dimensional scanning.

As another example, to implement steering mechanism 340, a one-dimensional mechanical scanner can be used with an array or a large number of single-point transceivers. Specifically, the transceiver array can be mounted on a rotating platform to achieve 360-degree horizontal field of view. Alternatively, a static transceiver array can be combined with the one-dimensional mechanical scanner. A one-dimensional mechanical scanner comprises polygon mirror(s), oscillating mirror(s), rotating prism(s), rotating tilt mirror surface(s) for obtaining a forward-looking horizontal field of view. Steering mechanisms using mechanical scanners can provide robustness and reliability in high volume production for automotive applications.

As another example, to implement steering mechanism 340, a two-dimensional transceiver can be used to generate a scan image or a 3D point cloud directly. In some embodiments, a stitching or micro shift method can be used to improve the resolution of the scan image, or the field of view being scanned. For example, using a two-dimensional transceiver, signals generated at one direction (e.g., the horizontal direction) and signals generated at the other direction (e.g., the vertical direction) may be integrated, interleaved, and/or matched to generate a higher or full resolution image or 3D point cloud representing the scanned FOV.

Some implementations of steering mechanism 340 comprise one or more optical redirection elements (e.g., mirrors or lens) that steer return light signals (e.g., by rotating, vibrating, or directing) along a receive path to direct the return light signals to optical receiver and light detector 330. The optical redirection elements that direct light signals along the transmitting and receiving paths may be the same components (e.g., shared), separate components (e.g., dedicated), and/or a combination of shared and separate components. This means that in some cases the transmitting and receiving paths are different although they may partially overlap (or in some cases, substantially overlap).

With reference still to FIG. 3 , LiDAR system 300 further comprises control circuitry 350. Control circuitry 350 can be configured and/or programmed to control various parts of the LiDAR system 300 and/or to perform signal processing. In a typical system, control circuitry 350 can be configured and/or programmed to perform one or more control operations including, for example, controlling laser source 310 to obtain desired laser pulse timing, repetition rate, and power; controlling steering mechanism 340 (e.g., controlling the speed, direction, and/or other parameters) to scan the FOV and maintain pixel registration/alignment; controlling optical receiver and light detector 330 (e.g., controlling the sensitivity, noise reduction, filtering, and/or other parameters) such that it is an optimal state; and monitoring overall system health/status for functional safety.

Control circuitry 350 can also be configured and/or programmed to perform signal processing to the raw data generated by optical receiver and light detector 330 to derive distance and reflectance information, and perform data packaging and communication to vehicle perception and planning system 220 (shown in FIG. 2 ). For example, control circuitry 350 determines the time it takes from transmitting a light pulse until a corresponding return light pulse is received; determines when a return light pulse is not received for a transmitted light pulse; determines the direction (e.g., horizontal and/or vertical information) for a transmitted/return light pulse; determines the estimated range in a particular direction; and/or determines any other type of data relevant to LiDAR system 300. Other functions can include controlling laser timing and power, controlling the rastering mechanism and keeping the pixel registration, maintaining the optical transceivers in the optimal state and monitoring the system health and status for functional safety.

LiDAR system 300 can be disposed in a vehicle, which may operate in many different environments including hot or cold weather, rough road conditions that may cause intense vibration, high or low humidity, dusty areas, etc. Therefore, in some embodiments, optical and/or electronic components of LiDAR system 300 (e.g., optics in transmitter 320, optical receiver and light detector 330, and steering mechanism 340) are disposed or configured in such a manner to maintain long term mechanical and optical stability. For example, components in LiDAR system 300 may be secured and sealed such that they can operate under all conditions a vehicle may encounter. As an example, an anti-moisture coating and/or hermetic sealing may be applied to optical components of transmitter 320, optical receiver and light detector 330, and steering mechanism 340 (and other components that are susceptible to moisture). As another example, housing(s), enclosure(s), and/or window can be used in LiDAR system 300 for providing desired characteristics such as hardness, ingress protection (IP) rating, self-cleaning capability, resistance to chemical and resistance to impact, or the like. In addition, efficient and economical methodologies for assembling LiDAR system 300 may be used to meet the LiDAR operating requirements while keeping the cost low.

It is understood by a person of ordinary skill in the art that FIG. 3 and the above descriptions are for illustrative purposes only, and a LiDAR system can include other functional units, blocks, or segments, and can include variations or combinations of these above functional units, blocks, or segments. For example, LiDAR system 300 can also include other components not depicted in FIG. 3 , such as power buses, power supplies, LED indicators, switches, etc. Additionally, other connections among components may be present, such as a direct connection between light source 310 and optical receiver and light detector 330 so that light detector 330 can accurately measure the time from when light source 310 transmits a light pulse until light detector 330 detects a return light pulse.

These components shown in FIG. 3 are coupled together using communications paths 312, 314, 322, 332, 342, 352, and 362. These communications paths represent communication (bidirectional or unidirectional) among the various LiDAR system components but need not be physical components themselves. While the communications paths can be implemented by one or more electrical wires, busses, or optical fibers, the communication paths can also be wireless channels or open-air optical paths so that no physical communication medium is present. For example, in one exemplary LiDAR system, communication path 314 includes one or more optical fibers; communication paths 332 and 352 represents an optical path; and communication paths 312, 322, 342, and 362 are all electrical wires that carry electrical signals. The communication paths can also include more than one of the above types of communication mediums (e.g., they can include an optical fiber and an optical path, or one or more optical fibers and one or more electrical wires).

As described above, some LiDAR systems use the time-of-flight (TOF) of light signals (e.g., light pulses) to determine the distance to objects in a light path. For example, with reference to FIG. 5A, an exemplary LiDAR system 500 includes a laser light source (e.g., a fiber laser), a steering system (e.g., a system of one or more moving mirrors), and a light detector (e.g., a photon detector with one or more optics). LiDAR system 500 can be implemented using, for example, LiDAR system 300 described above. LiDAR system 500 transmits a light pulse 502 along light path 504 as determined by the steering system of LiDAR system 500. In the depicted example, light pulse 502, which is generated by the laser light source, is a short pulse of laser light. Further, the signal steering system of the LiDAR system 500 is a pulsed-signal steering system. However, it should be appreciated that LiDAR systems can operate by generating, transmitting, and detecting light signals that are not pulsed and derive ranges to an object in the surrounding environment using techniques other than time-of-flight. For example, some LiDAR systems use frequency modulated continuous waves (i.e., “FMCW”). It should be further appreciated that any of the techniques described herein with respect to time-of-flight based systems that use pulsed signals also may be applicable to LiDAR systems that do not use one or both of these techniques.

Referring back to FIG. 5A (e.g., illustrating a time-of-flight LiDAR system that uses light pulses), when light pulse 502 reaches object 506, light pulse 502 scatters or reflects to generate a return light pulse 508. Return light pulse 508 may return to system 500 along light path 510. The time from when transmitted light pulse 502 leaves LiDAR system 500 to when return light pulse 508 arrives back at LiDAR system 500 can be measured (e.g., by a processor or other electronics, such as control circuitry 350, within the LiDAR system). This time-of-flight combined with the knowledge of the speed of light can be used to determine the range/distance from LiDAR system 500 to the portion of object 506 where light pulse 502 scattered or reflected.

By directing many light pulses, as depicted in FIG. 5B, LiDAR system 500 scans the external environment (e.g., by directing light pulses 502, 522, 526, 530 along light paths 504, 524, 528, 532, respectively). As depicted in FIG. 5C, LiDAR system 500 receives return light pulses 508, 542, 548 (which correspond to transmitted light pulses 502, 522, 530, respectively). Return light pulses 508, 542, and 548 are generated by scattering or reflecting the transmitted light pulses by one of objects 506 and 514. Return light pulses 508, 542, and 548 may return to LiDAR system 500 along light paths 510, 544, and 546, respectively. Based on the direction of the transmitted light pulses (as determined by LiDAR system 500) as well as the calculated range from LiDAR system 500 to the portion of objects that scatter or reflect the light pulses (e.g., the portions of objects 506 and 514), the external environment within the detectable range (e.g., the field of view between path 504 and 532, inclusively) can be precisely mapped or plotted (e.g., by generating a 3D point cloud or images).

If a corresponding light pulse is not received for a particular transmitted light pulse, then it may be determined that there are no objects within a detectable range of LiDAR system 500 (e.g., an object is beyond the maximum scanning distance of LiDAR system 500). For example, in FIG. 5B, light pulse 526 may not have a corresponding return light pulse (as illustrated in FIG. 5C) because light pulse 526 may not produce a scattering event along its transmission path 528 within the predetermined detection range. LiDAR system 500, or an external system in communication with LiDAR system 500 (e.g., a cloud system or service), can interpret the lack of return light pulse as no object being disposed along light path 528 within the detectable range of LiDAR system 500.

In FIG. 5B, light pulses 502, 522, 526, and 530 can be transmitted in any order, serially, in parallel, or based on other timings with respect to each other. Additionally, while FIG. 5B depicts transmitted light pulses as being directed in one dimension or one plane (e.g., the plane of the paper), LiDAR system 500 can also direct transmitted light pulses along other dimension(s) or plane(s). For example, LiDAR system 500 can also direct transmitted light pulses in a dimension or plane that is perpendicular to the dimension or plane shown in FIG. 5B, thereby forming a 2-dimensional transmission of the light pulses. This 2-dimensional transmission of the light pulses can be point-by-point, line-by-line, all at once, or in some other manner. A point cloud or image from a 1-dimensional transmission of light pulses (e.g., a single horizontal line) can generate 2-dimensional data (e.g., (1) data from the horizontal transmission direction and (2) the range or distance to objects). Similarly, a point cloud or image from a 2-dimensional transmission of light pulses can generate 3-dimensional data (e.g., (1) data from the horizontal transmission direction, (2) data from the vertical transmission direction, and (3) the range or distance to objects). In general, a LiDAR system performing an n-dimensional transmission of light pulses generates (n+1) dimensional data. This is because the LiDAR system can measure the depth of an object or the range/distance to the object, which provides the extra dimension of data. Therefore, a 2D scanning by a LiDAR system can generate a 3D point cloud for mapping the external environment of the LiDAR system.

The density of a point cloud refers to the number of measurements (data points) per area performed by the LiDAR system. A point cloud density relates to the LiDAR scanning resolution. Typically, a larger point cloud density, and therefore a higher resolution, is desired at least for the region of interest (ROI). The density of points in a point cloud or image generated by a LiDAR system is equal to the number of pulses divided by the field of view. In some embodiments, the field of view can be fixed. Therefore, to increase the density of points generated by one set of transmission-receiving optics (or transceiver optics), the LiDAR system may need to generate a pulse more frequently. In other words, a light source with a higher pulse repetition rate (PRR) is needed. On the other hand, by generating and transmitting pulses more frequently, the farthest distance that the LiDAR system can detect may be limited. For example, if a return signal from a distant object is received after the system transmits the next pulse, the return signals may be detected in a different order than the order in which the corresponding signals are transmitted, thereby causing ambiguity if the system cannot correctly correlate the return signals with the transmitted signals.

To illustrate, consider an exemplary LiDAR system that can transmit laser pulses with a repetition rate between 500 kHz and 1 MHz. Based on the time it takes for a pulse to return to the LiDAR system and to avoid mix-up of return pulses from consecutive pulses in a conventional LiDAR design, the farthest distance the LiDAR system can detect may be 300 meters and 150 meters for 500 kHz and 1 MHz, respectively. The density of points of a LiDAR system with 500 kHz repetition rate is half of that with 1 MHz. Thus, this example demonstrates that, if the system cannot correctly correlate return signals that arrive out of order, increasing the repetition rate from 500 kHz to 1 MHz (and thus improving the density of points of the system) may reduce the detection range of the system. Various techniques are used to mitigate the tradeoff between higher PRR and limited detection range. For example, multiple wavelengths can be used for detecting objects in different ranges. Optical and/or signal processing techniques are also used to correlate between transmitted and return light signals.

Various systems, apparatus, and methods described herein may be implemented using digital circuitry, or using one or more computers using well-known computer processors, memory units, storage devices, computer software, and other components. Typically, a computer includes a processor for executing instructions and one or more memories for storing instructions and data. A computer may also include, or be coupled to, one or more mass storage devices, such as one or more magnetic disks, internal hard disks and removable disks, magneto-optical disks, optical disks, etc.

Various systems, apparatus, and methods described herein may be implemented using computers operating in a client-server relationship. Typically, in such a system, the client computers are located remotely from the server computers and interact via a network. The client-server relationship may be defined and controlled by computer programs running on the respective client and server computers. Examples of client computers can include desktop computers, workstations, portable computers, cellular smartphones, tablets, or other types of computing devices.

Various systems, apparatus, and methods described herein may be implemented using a computer program product tangibly embodied in an information carrier, e.g., in a non-transitory machine-readable storage device, for execution by a programmable processor; and the method processes and steps described herein, including one or more of the steps of FIG. 11 , may be implemented using one or more computer programs that are executable by such a processor. A computer program is a set of computer program instructions that can be used, directly or indirectly, in a computer to perform a certain activity or bring about a certain result. A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

A high-level block diagram of an exemplary apparatus that may be used to implement systems, apparatus and methods described herein is illustrated in FIG. 6 . Apparatus 600 comprises a processor 610 operatively coupled to a persistent storage device 620 and a main memory device 630. Processor 610 controls the overall operation of apparatus 600 by executing computer program instructions that define such operations. The computer program instructions may be stored in persistent storage device 620, or other computer-readable medium, and loaded into main memory device 630 when execution of the computer program instructions is desired. For example, processor 610 may be used to implement one or more components and systems described herein, such as control circuitry 350 (shown in FIG. 3 ), vehicle perception and planning system 220 (shown in FIG. 2 ), and vehicle control system 280 (shown in FIG. 2 ). Thus, the method steps of FIG. 11 can be defined by the computer program instructions stored in main memory device 630 and/or persistent storage device 620 and controlled by processor 610 executing the computer program instructions. For example, the computer program instructions can be implemented as computer executable code programmed by one skilled in the art to perform an algorithm defined by the method steps of FIG. 11 . Accordingly, by executing the computer program instructions, the processor 610 executes an algorithm defined by the methods of FIG. 11 . Apparatus 600 also includes one or more network interfaces 680 for communicating with other devices via a network. Apparatus 600 may also include one or more input/output devices 690 that enable user interaction with apparatus 600 (e.g., display, keyboard, mouse, speakers, buttons, etc.).

Processor 610 may include both general and special purpose microprocessors and may be the sole processor or one of multiple processors of apparatus 600. Processor 610 may comprise one or more central processing units (CPUs), and one or more graphics processing units (GPUs), which, for example, may work separately from and/or multi-task with one or more CPUs to accelerate processing, e.g., for various image processing applications described herein. Processor 610, persistent storage device 620, and/or main memory device 630 may include, be supplemented by, or incorporated in, one or more application-specific integrated circuits (ASICs) and/or one or more field programmable gate arrays (FPGAs).

Persistent storage device 620 and main memory device 630 each comprise a tangible non-transitory computer readable storage medium. Persistent storage device 620, and main memory device 630, may each include high-speed random access memory, such as dynamic random access memory (DRAM), static random access memory (SRAM), double data rate synchronous dynamic random access memory (DDR RAM), or other random access solid state memory devices, and may include non-volatile memory, such as one or more magnetic disk storage devices such as internal hard disks and removable disks, magneto-optical disk storage devices, optical disk storage devices, flash memory devices, semiconductor memory devices, such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM), digital versatile disc read-only memory (DVD-ROM) disks, or other non-volatile solid state storage devices.

Input/output devices 690 may include peripherals, such as a printer, scanner, display screen, etc. For example, input/output devices 690 may include a display device such as a cathode ray tube (CRT), plasma or liquid crystal display (LCD) monitor for displaying information to a user, a keyboard, and a pointing device such as a mouse or a trackball by which the user can provide input to apparatus 600.

Any or all of the functions of the systems and apparatuses discussed herein may be performed by processor 610, and/or incorporated in, an apparatus or a system such as LiDAR system 300. Further, LiDAR system 300 and/or apparatus 600 may utilize one or more neural networks or other deep-learning techniques performed by processor 610 or other systems or apparatuses discussed herein.

One skilled in the art will recognize that an implementation of an actual computer or computer system may have other structures and may contain other components as well, and that FIG. 6 is a high-level representation of some of the components of such a computer for illustrative purposes.

Embodiments of present invention are described below. In various embodiments of the present invention, an apparatus for a light detection and ranging (LiDAR) scanning system for at least partial integration with a vehicle is disclosed. The apparatus comprises an optical core assembly including an oscillating reflective element, an optical polygon element, and transmitting and collection optics. The apparatus includes a first exterior surface at least partially bounded by at least a first portion of a vehicle roof or at least a portion of a vehicle windshield. A surface profile of the first exterior surface aligns with a surface profile associated with at least one of the first portion of the vehicle roof or the portion of the vehicle windshield. A combination of the first exterior surface and the one or more additional exterior surfaces form a housing enclosing the optical core assembly including the oscillating reflective element, the optical polygon element, and the transmitting and collection optics.

FIG. 7 illustrates a perspective view 707 and a side view 710 of several mounting options for an exemplary LiDAR system on autonomous driver motor vehicles 705 and 720 respectively. Exemplary LiDAR system 707 is a top mounted LiDAR system of a form used in many autonomous driver vehicle test fleets (e.g., Waymo), which shows a large and bulky LiDAR system that is mounted on top of the vehicle roof with a metal roof rack. This size of the LiDAR and rack mount (which occupies nearly all of the vehicle roof) and mounting type of LiDAR system may work for autonomous driver vehicle test fleets that are mapping and learning driving routes through cities, but will not work well for high-volume production or for consumer vehicles. Side view 710 shows a exemplary LiDAR system having a slim, more aerodynamic design that is integrated into the roof of the vehicle adjacent to the top portion of the vehicle's windshield. In one embodiment of the invention, the LiDAR system 710 is positioned proximate to a middle position of a windshield, e.g., between two A-pillars of the vehicle.

FIG. 8 illustrates a front view of an exemplary LiDAR system 810 integrated into a roof and windshield portion of autonomous driver motor vehicle 800, showing some key considerations for integration of a LiDAR system into an aerodynamic design of a motor vehicle. In some embodiments of the invention, the LiDAR system is mounted near the top portion or roof of the vehicle for optimal visibility, performance, and Field-of-View (FoV). Thus, height for a top-mounted LiDAR system design should be minimized where possible in order to reduce aerodynamic drag. In addition, exposed dimensions of the LiDAR design integration should be contoured to fit the overall vehicle profile. Finally, if more space is needed for the LiDAR system components, the lateral dimensions of the LiDAR system may be expanded as needed in order to preserve the low aerodynamic contour profile.

FIG. 9 illustrates a side profile view and a zoom-in side view of an exemplary LiDAR system 910 in an autonomous driver motor vehicle 900 of some embodiments of the disclosed invention. Exemplary LiDAR system design 910 comprises a contour design to fit a top profile of vehicle 900. The LiDAR system 910 comprises an optical core assembly including an optical engine 925. The optical engine 925 is enclosed by a first exterior surface 915 at least partially bounded by at least a first portion of a vehicle roof or at least a portion of a vehicle windshield, wherein a surface profile of the first exterior surface aligns with a surface profile associated with at least one of the first portion of the vehicle roof or the portion of the vehicle windshield. The optical engine 925 is further enclosed by one or more additional exterior surfaces 920, wherein a combination of the first exterior surface and the one or more additional exterior surfaces form a housing enclosing the optical engine 925, which includes an oscillating reflective element, an optical polygon element, and transmitting and collection optics to be described further below.

The overall design goals of LiDAR system 910 in embodiments of the disclosed invention is to keep the overall height as low as possible. The goals include reducing the height of scanning elements including the oscillating reflective element and an optical polygon element, and reducing the height of transmitting and collection optics including a transceiver. A polygon motor (not shown) may be located and/or embedded inside the optical polygon element to further reduce the height and space requirements of the scanning elements. A further design goal includes minimizing a gap between the scanning elements and the transceiver. The contour design further includes having a tapered profile from front to back, with a larger area adjacent to the front of the vehicle to maximize FoV and aperture. The top surface 920 of the system unit 910 is kept substantially flat or parallel and/or flush with the vehicle roof to minimize protrusion, while the bottom surface 915 of system 910 gradually slopes upward from the front of the vehicle 900 along the profile of the windshield to where the windshield meets the vehicle roof, in order to fit the vehicle's upper contours. Also in keeping with the goals of keeping the profile tapered from front to back and keeping the overall height as low as possible, other parts of the LiDAR system 910 are spread to both sides of optical engine 925.

FIG. 10 illustrates a flow diagram 1000 for a LiDAR signal chain according to embodiments of the disclosed invention. FIG. 11 illustrates the path of a LiDAR signal using an exemplary apparatus for a LiDAR optical engine 1100 according to embodiments of the disclosed invention, which will be discussed below in conjunction with FIG. 10 .

Fiber laser 1110 may be considered a laser source 310 and may output laser light as shown in laser generation step 1010 of FIG. 10 . Laser light may be directed through splitter 1020 and/or transmission fiber array 1160. As discussed herein above, laser beams may then be directed through collimator 1155 which is configured to collect the diverging laser beams and produce more parallel optical beams with reduced or minimum divergence. Beam steering step 1020 may be accomplished by directing or scanning the one or more of the collimated laser beams in multiple dimensions (e.g., in both a horizontal and a vertical dimension) to a FoV to help map the environment. The laser beams may be directed through various optics such as mirrors and lenses, including but not limited to galvo mirror 1180, followed by polygon mirror 1150, in that order or a different order. As discussed above herein, the laser light scanned to FoV may be scattered or reflected by an object 1140 in the FoV, propagating through free space in accordance with step 1030.

At least a portion of the scattered or reflected light returns to LiDAR optical engine 1100 in return light collection step 1040. LiDAR optical engine 1100 may include an optical receiver configured to collect the return light from the FoV, as discussed herein above, and may include optics for receiving, redirecting, focusing, amplifying and/or filtering return light from the FoV. LiDAR optical engine 1100 includes exemplary optical receiver apparatus including, e.g., polygon mirror 1150 and galvo mirror 1180. LiDAR optical engine 1100 also includes collection lens 1170 (e.g., a single plano-convex lens or lens group) as part of its exemplary optical receiver apparatus to collect and/or focus the collected return light onto a light detector in step 1050, e.g., by using a receive fiber array 1190 coupled to an avalanche photodetector (APD) 1150, or in some other embodiments, receive fiber array 1190 and APD 1150 may be replaced with an APD array (not shown). Receiver signal conversion occurs in step 1060 as discussed above to generate depth and/or distance information of object(s) in the FoV.

FIG. 12 shows a cross-sectional view of a tapered design 1200 for a LiDAR system in accordance with one embodiment of the disclosed invention. Transmission fiber array 1260 may reflect transmitted light beams off of galvo mirror 1280 and polygon mirror 1220 which is operably configured to rotate as powered by polygon motor 1230 which then exit through window 1210 and propagate through free space as transmission beams 1295. Received light beams 1290 may return to LiDAR system 1200 through front window 1210 as part of a returned light collection step as discussed above. LiDAR optical engine 1200 may include an optical receiver configured to collect the return light from the FoV, as discussed herein above, and may include optics for receiving, redirecting, focusing, amplifying and/or filtering return light from the FoV. LiDAR system 1200 includes exemplary optical receiver apparatus including, e.g., polygon mirror 1220 and galvo mirror 1280. LiDAR optical engine 1200 also includes collection lens 1270 (e.g., a single plano-convex lens or lens group) as part of its exemplary optical receiver apparatus to collect and/or focus the collected return light onto a light detector, e.g., by using a receive fiber array 1250. A cable connector 1240 may be configured to connect the components of LiDAR system 1200 to power and vehicle computing and/or data systems in other parts of the vehicle.

In some embodiments of the disclosed invention, to minimize protrusion of the LiDAR system 1200 from the vehicle roof, a portion of the LiDAR system 1200 may be positioned below the vehicle roof and windshield inside the vehicle cabin. For example, as shown in the exemplary LiDAR system tapered design shown in FIG. 12 , galvo mirror 1280, collection lens 1270 and receive fiber array 1250, among other components in system 1200, may lie partially or entirely below the vehicle roof line 1205. In one embodiment of the disclosed invention as shown in FIG. 12 , the updated roof line may lie approximately 11 degrees from the horizontal. In the embodiment of the disclosed invention as shown in FIG. 12 , the length of the tapered LiDAR system design 1200 is approximately 143 mm (not including the cable connector 1240), and the height of tapered LiDAR system design 1200 is approximately 60 mm at its highest point adjacent to front window 1210, although dimensions larger or smaller (e.g., less than or equal to 50 mm overall height) than those disclosed herein are within the scope of the disclosed invention. In particular, a LiDAR system with a contoured exterior design to fit seamlessly at the front top of a vehicle is disclosed with a height of less than or equal to approximately 40 or 45 mm across the whole LiDAR system is contemplated within the scope of the disclosed invention. Furthermore, a top exterior surface of the LiDAR system housing may be blended in line with a top surface of the vehicle roof, and a bottom surface of the LiDAR system may be blended in line with interior upper surface of the vehicle cabin. In addition, the back surface of the LiDAR system may be tapered to fit against a front top beam of the vehicle.

In some embodiments of the disclosed invention, a LiDAR system is designed with a special optical engine design to fit inside a contoured exterior enclosure as described above, including a low-profile polygon scanning element with a motor buried inside the scanner mirror. Furthermore, in some embodiments the polygon scanning element may be positioned above the transceiver module. Finally, a collection lens (e.g., 1270 in FIG. 12 ) may be asymmetrically cut with a first surface 1272, a second surface 1276, and a third surface 1274 to focus the returned scattered light upward as shown in FIG. 12 , thus reducing the height requirement towards the rear of the LiDAR system 1200 as shown in FIG. 12 .

Keeping in mind that the receiving aperture requirements may be fixed or less flexible in order for object detection performance specifications to be met, other strategies to reduce the height of the optical engine may be employed. For example, by stretching the size of the polygon mirror, the polygon height may be reduced while the same receiving aperture may be maintained. In addition, by cutting a portion of the collection lens from the top and bottom, the height of the receiver sub-assembly may be further reduced.

In some embodiments of the disclosed invention, a LiDAR system is designed with a compact transceiver module for integration at the front top of a vehicle, including a low profile collection lens that reduces the module height while maintaining a large receiving aperture. FIG. 13 shows two exemplary embodiments of a positioning a transmission beam in order to reduce the height of the optical engine. In one exemplary embodiment 1320 shown in FIG. 13 , the size of a transmitter sub-assembly 1325 may be minimized and included inside of the collection lens 1330 by cutting slots inside the collection lens to position the transmitter sub-assembly parts. Embodiment 1320 of FIG. 13 is utilized in the exemplary LiDAR system embodiment shown in FIG. 12 . In some embodiments of the disclosed invention, an optical beam-shifting system (e.g., a periscope prism) may be used to move the transmitter beam into the receiving aperture as shown in embodiment 1310 wherein the periscope prism includes two reflecting surfaces 1312 and 1314 (e.g., mirrors) disposed substantially parallel to each other in FIG. 13 . In this manner, the transmitter may sit outside the collection lens and the lens does not have to be cut open.

FIG. 14 illustrates a top view of an exemplary LiDAR tapered system design 1400 in accordance with embodiments of the disclosed invention. Galvo mirror 1450 is positioned near the front portion of the system unit adjacent to window 1455, and polygon 1460 is positioned toward the center of the system unit. Fiber laser module 1440 containing the laser light source and transmission fiber array may be positioned adjacent to polygon 1460. Receive transmission fiber array 1480 is positioned adjacent to the polygon 1460, and is operably connected to the avalanche photo diodes (APD) 1430 and APD Board 1420, which are also connected to a main system board 1410. In addition, motor control board 1490 for operating the oscillating reflective elements (e.g., polygon 1460) is connected to main system board 1410. Connectors 1470 may also be connected to main system board 1410, and are positioned towards the rear of the system unit. In one exemplary embodiment, system 1400 is approximately 180 mm wide at the front portion, and extends approximately 143 mm in length towards the rear of the vehicle.

FIG. 15 illustrates a top view of an exemplary LiDAR system design 1500 in accordance with one embodiment of the disclosed invention. Galvo mirror 1550 is positioned near the front portion of the system unit 1500, and polygon 1560 is positioned toward the center of the system unit. Fiber laser module 1540 containing the laser light source and transmission fiber array may be positioned adjacent to polygon 1460. Receive transmission fiber array (not shown) may be positioned adjacent to the polygon 1560, and is operably connected to the avalanche photo diodes (APD) 1530 which are operably connected to APD board 1520, which are also connected to a main system board 1510, which may contain elements for motor control for operating the oscillating reflective elements (e.g., polygon 1560). Connectors 1570 may also be connected to main system board 1510, and may be positioned near one side of the system unit. In one exemplary embodiment, system 1500 extends approximately 143 mm in length towards the rear of the vehicle.

The foregoing specification is to be understood as being in every respect illustrative and exemplary, but not restrictive, and the scope of the invention disclosed herein is not to be determined from the specification, but rather from the claims as interpreted according to the full breadth permitted by the patent laws. It is to be understood that the embodiments shown and described herein are only illustrative of the principles of the present invention and that various modifications may be implemented by those skilled in the art without departing from the scope and spirit of the invention. Those skilled in the art could implement various other feature combinations without departing from the scope and spirit of the invention. 

What is claimed is:
 1. An apparatus of a light detection and ranging (LiDAR) scanning system for at least partial integration with a vehicle, the apparatus comprising: an optical core assembly including an oscillating reflective element, an optical polygon element, and transmitting and collection optics, wherein the oscillating reflective element is positioned at a lower position compared with an optic axis of transmission light beams directed by the optical polygon element, at least a portion of the optical polygon element is positioned above a vehicle roof line, and at least a portion of the oscillating reflective element and the transmitting and collection optics is positioned below the vehicle roof line; a first exterior surface at least partially bounded by at least a first portion of a vehicle roof or at least a portion of a vehicle windshield, wherein a surface profile of the first exterior surface aligns with a surface profile associated with at least one of the first portion of the vehicle roof or the portion of the vehicle windshield; and one or more additional exterior surfaces, wherein a combination of the first exterior surface and the one or more additional exterior surfaces form a housing enclosing the oscillating reflective element, the optical polygon element, and the transmitting and collection optics.
 2. The apparatus of claim 1, wherein the optical core assembly is positioned proximate to a middle position between two A-pillars of the vehicle.
 3. The apparatus of claim 1, wherein the surface profile of the first exterior surface comprises a sloped or curved portion that aligns with a sloped or curved portion of the surface profile associated with at least one of the first portion of the vehicle roof or the portion of the vehicle windshield.
 4. The apparatus of claim 1, wherein the one or more additional exterior surfaces further comprise a second exterior surface having a surface profile that at least partially aligns with a surface profile of a second portion of the vehicle roof.
 5. The apparatus of claim 4, wherein the surface profile of the second exterior surface comprises a substantially planar portion that aligns with a substantially planar portion of the surface profile of the second portion of the vehicle roof.
 6. The apparatus of claim 4, wherein an amount of elevation difference between the second exterior surface and the second portion of the vehicle roof is less than or equal to approximately 50 mm.
 7. The apparatus of claim 1, wherein the lateral dimensions of at least one of the oscillating reflective element, the optical polygon element, and the transmitting and collection optics are configured to be greater than or equal to 150% of height dimensions of the same element.
 8. The apparatus of claim 1, wherein the housing has a tapered profile from a forward-facing end of the housing to a rear-facing end of the housing.
 9. The apparatus of claim 8, wherein the oscillating reflective element is disposed in a first inner portion of the housing, the first inner portion of the housing being proximate to the forward-facing end of the housing, the oscillating reflective element being positioned proximate to the first exterior surface.
 10. The apparatus of claim 4, wherein the optical polygon element is disposed proximate to the second exterior surface, the optical polygon element comprising a plurality of facets tilted with respect to a rotation axis of the optical polygon element.
 11. The apparatus of claim 1, wherein the transmitting and collection optics comprise a plurality of transmitter channels configured to deliver the transmission light beams to the oscillating reflective element.
 12. The apparatus of claim 11, wherein the transmitting and collection optics further comprise: a collimation lens optically coupled to the plurality of transmitter channels to receive the transmission light beams; and a collection lens disposed to receive and redirect returning light generated based on the transmission light beams.
 13. The apparatus of claim 12, further comprising an optical beam-shifting system optically coupled to the collimation lens, wherein the optical beam-shifting system redirects a plurality of collimated transmission light beams such that at least a part of the collimated transmission light beams is positioned within an optical receiving aperture of the collection lens.
 14. The apparatus of claim 13, wherein the optical beam-shifting system comprises one or more prisms, lenses, and mirrors configured to redirect a plurality of collimated transmission light beams such that the redirected collimated transmission light beams are substantially parallel to the collimated transmission light beams.
 15. The apparatus of claim 13, wherein the optical beam-shifting system comprises a periscope prism including two reflecting surfaces disposed substantially parallel to each other.
 16. The apparatus of claim 11, wherein the transmitting and collection optics further comprise a collection lens having an opening, wherein the plurality of transmitter channels is at least partially disposed in the opening to deliver the transmission light beams to the oscillating reflective element.
 17. The apparatus of claim 16, wherein the opening is positioned proximate to an edge of the collection lens and has a dimension configured based at least in part on an optical receiving aperture requirement.
 18. The apparatus of claim 16, wherein the collection lens has an asymmetric shape with a reduced height relative to a corresponding symmetrically shaped collection lens.
 19. The apparatus of claim 18, wherein the transmitting and collection optics further comprise a plurality of receiving channels disposed inside the housing at a position based on a focal length of the collection lens, wherein the collection lens comprises a first surface portion optically configured to direct light to the plurality of receiving channels.
 20. The apparatus of claim 19, wherein the collection lens further comprises a second surface portion and a third surface portion, wherein both the second surface portion and the third surface portion intersect with the first surface portion.
 21. The apparatus of claim 20, wherein the second surface portion is positioned proximate to the optical polygon element, and wherein an optical axis of the collection lens is closer to the second surface portion than to the third surface portion.
 22. The apparatus of claim 19, wherein the plurality of receiving channels is positioned proximate to the optical polygon element wherein a path of the plurality of receiving channels is configured to align with a tapered profile of the housing.
 23. The apparatus of claim 19, wherein the plurality of receiving channels is disposed proximate to the rear-facing end of the housing.
 24. The apparatus of claim 11, wherein the oscillating reflective element is configured to redirect the transmission light beams provided by the plurality of transmitter channels to the optical polygon element.
 25. The apparatus of claim 1, wherein a combination of the optical polygon element and the oscillating reflective element, when moving with respect to each other, steers the transmission light beams both horizontally and vertically to illuminate one or more objects in a partial field-of-view of the LiDAR apparatus; and obtains return light generated based on the illumination of the one or more objects.
 26. The apparatus of claim 1, wherein the optical polygon element has a height less than or equal to about 20 mm.
 27. The apparatus of claim 1, wherein the optical polygon element comprises a polygon motor positioned inside the optical polygon element.
 28. The apparatus of claim 1, wherein the optical core assembly further comprises a window forming a portion of the one or more additional exterior surfaces of the housing.
 29. The apparatus of claim 28, wherein the window is tilted at an angle configured based on at least one of: an orientation of the optical polygon element, an orientation of the oscillating reflective element, and an orientation of the transmitting and collection optics.
 30. The apparatus of claim 1, wherein the transmitting and collection optics comprise four or more transmitter channels and four or more receiving channels. 